The Yoomi is a bottle and warmer in one, that warms a baby’s feeding to the natural temperature of breast milk in 60 seconds.

As I mentioned in my post about my breastfeeding experiences, neither of my kids were wild about the bottle. I suspect my milk has excess lipase (so I am definitely going to try scalding it next time before storing!) but I’m guessing it’s probably also because I really had no clue how to warm it. You don’t want to microwave or overheat breast milk, not just because of potential hot spots, but also because it can destroy some of the good stuff in it. I tried microwaving water, then putting the bottle in it to warm…took forever and I was never sure if it was warm enough. Tried running it under hot water…same thing. I never bought a bottle warmer since bottles were so rare in our house anyway, but a warmer can’t be used away from home, doesn’t necessarily heat it evenly or to the ideal temperature, and it warms the whole bottle at once, so it gets cool as the baby drinks.

Still, I would love to have a bottle that’s easy to use and heat, so that there’s the option of me running out to the store by myself, or maybe even getting out with my husband.

The Yoomi self-warming bottle has to be one of the coolest (warmest? Har har) ideas I’ve seen. It consists of a BPA free, easy to hold bottle (available in 5 oz and 8 oz sizes), a naturally shaped nipple with anti colic vents (available in slow, medium and fast flow), a collar to hold it on obviously, cap, and the warmer.

Clearly, the warmer is what makes it stand out. The warmer warms milk to the natural temperature of breast milk (89.6-93.2 degrees) in 60 seconds, without plugs, batteries, hot water etc. The warmer uses the same gel that is used in hand warmer packets, which is a concentrated, non-toxic salt solution (also used in ice cream.) Yoomi has also added a food grade colorant and Bitrex (a safe but bitter substance) so that if the warmer leaked, not only would you see it, but the baby would refuse to consume the feeding.

The Yoomi came with a fantastic pamphlet that tells you just about everything you need to know.

The first thing you need to do is charge the warmer, which you do by boiling it for 25 minutes. You can also use a steam sterilizer with 4x the recommended amount of water, but the warmer cannot be placed in the microwave.

I used a 3 quart pot the first time, but a 4 quart would have worked much better, since so much water evaporates during the boiling time!

Once the water was at a full boil, I lowered the warmer in with tongs, and boiled it for 25 minutes.

Carefully remove the warmer (I used the tongs again) and allow it to cool on it’s side, on a clean surface for an hour and 15 minutes. The orange button turns blue after you boil it; it should be back to orange, cool to the touch, and rattle when shaken before you use it. You shouldn’t depress the button before it’s fully cooled, or you could damage the warmer. You can also cool it more quickly by running it under cool water, but of course it will no longer be sterile.

If the warmer sounds slushy, rather than rattl-ey, you may not have boiled it long enough. I believe not having quite enough water the first time caused me to have a slightly sloshy sound (and it also took a bit longer for the warmer to fully activate/button to turn blue.) If you’ve used enough water, but this happens, try adding 5 minutes to the boil time.

Use the bottle to pick the warmer up to assemble it. You can store the charged warmer, and it will be ready to use pretty much indefinitely. You can go ahead and fill the bottle, and store the whole shebang in the fridge, and it will still work (perfect for outings with Dad, or to take to the babysitter.) The Yoomi can be used with breast milk or pre-mixed formula.

For my photo demo, I used water stored in the fridge; this was it’s temp before.

When you’re ready to use it, just press the orange button and wait 30 seconds, then turn the bottle upside down and wait another 30 seconds. If you stare at the bottle while you’re waiting, you’ll see the orange start to fade. When it’s blue, you know it’s fully activated. As I said earlier, mine took a bit longer to reach this stage, I believe because I didn’t have it in quite enough water while boiling!

The Yoomi warms the feeding as it flows past the channels in the warmer, so it’s actually warming the milk as the baby drinks, rather than warming it all at once (and having it start to get cool while baby drinks.) So, I squeezed some of the warmed water out into the bottle cap to measure the temp. It took me a while to squeeze out enough to measure the temp, so it had cooled a bit by the time I managed to do it! This temperature is much like the natural temperature of breast milk (slightly cooler than your body temp), which makes it easier for the baby to go back and forth between breast and bottle. They are less likely to refuse it because it’s too hot or too cold, and they won’t develop a preference for extra-warm bottles. You cannot overheat the milk, so you never have to worry about the baby being burned. The warmer continues to warm for an hour, so the last drop will be just as warm as the first. You of course want to keep the bottle upside down during the feeding, so if the baby needs a break, put the cap on and place it upside down, so the milk in the nipple will be warm when baby is ready again.

The warmer can be used up to 100 times, or three months after it’s first use. I read this, but it didn’t sink in before I broke it out to test it, so I will have to buy another warmer before I can try it with the baby in December! Oops! Yoomi is working on a way to easily look at the warmer and know it’s ready to be replaced, but for now, you know if it doesn’t rattle when charged, the button doesn’t change color, or if the base of the warmer is permanently bulging out. It comes with a little chart to tick off each time you charge it.

Initially, I was a little overwhelmed by all the info, and unsure if I’d be able to figure it out, but it was really quite easy! I made a quick video demonstrating:

All the pieces are interchangeable, and the bottles can be used without the warmer. Either size bottle with nipple has an MSRP of $10.95. Nipples alone are $6.95 for a 2-pack, and a single warmer is $25.95. You save when you buy a bottle with warmer for $32.95. Initially, it seemed pricey to me but it’s really 25 cents per use, and it can be used anywhere, anytime, takes just 60 seconds, warms to the ideal temperature, and warms as you feed. No other warming method can do that.

FTC compliance: I received the pictured product at no cost in order to review it. I was not compensated for this post and all opinions are my own. This post contains a single Amazon affiliate link.

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Maria is the mother of 3, writing about cloth diapers & going green. You'll often find her juggling her preschooler and typing 1-handed in between sips of cold coffee.
Maria works with many companies within the cloth diaper industry and beyond, providing social media management, product development and other services.

Maria wants to live in a world where cloth diapers are the norm and moms can make parenting choices without judgement. When she’s not chasing her 13, 9 and 6-year old kids around, you might find her checking out the latest gadgets, organizing something (again) or exercising in the fresh air. Read More »